The invention relates to a chuck for non-circular ends of tool shanks, particularly screwdriver bits. The inventions provides such a chuck which has a bushing whose chamber corresponds to the non-circular cross section of the tool shank end and a ball which acts on the shank and is associated with a sleeve which is displaceable against spring action, the association of the ball with the sleeve being such that a clamping surface, which narrows down in wedge-shape towards the shank-receiving end of the chuck presses against the ball, in which connection the sleeve is displaceable in the direction of insertion of the shank for passage into a release position, the ball being received in a protruding wing, and the clamping surface being on the inner wall of an end ring which surrounds the edge of the bushing and the wing.
The advantages of this reside essentially in the fact that, upon displacement of the sleeve, the chuck will not be moved out of the drilling machine even in case of an insufficiently firm seat of the chuck in the holder. In one embodiment, the wing in one piece with the sleeve. Since the wing corresponds to a segment forming the non-circular cross section of the bushing, the sleeve can be displaced only in the longitudinal direction of the chuck (DE OS No. 32 43 389).
The object of the present invention is to provide and improve a chuck of this type in the manner that, for the same size, a greater torque can be transmitted, with improved adjustment and handling.